With the disapearance of the late Wisconsinan ice sheet, from the southern most tip of the Lake Ontario Basin, came a number of large glacial lakes which defined the early Champlain Sea as a freshwater body.  The retreat of the ice sheet was roughly in a south to north direction, along a similar path on which it advanced.  the retreat is said to have happened in five distinct phases;

Lake Iroquois - Watertown Phase
Lake Iroquois - Main Phase
Lake Frontenac Phase
Belleville Phase
Trenton (Champlain Sea) Phase

( It may be helpful to look over the regional setting before proceeding )

(Regional Setting)       MAIN PAGE         ( 1st   phase )